import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 666
 * Date: 2022-12-01
 * Time: 20:54
 */
public class test1 {
    public static void main(String[] args) {
        int[] arr=new int[10001];
        Scanner scanner = new Scanner(System.in);
        int a=0;
        while (scanner.hasNext()){
            arr[a++]=scanner.nextInt();
        }
        for (int i = 0; i < a; i++) {
            for (int j = i+1; j <a ; j++) {
                if(arr[i]==arr[j]){
                    System.out.println("yes");
                   return;
                }
            }
        }
        System.out.println("no");
    }
    public static void main1(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String a=scanner.nextLine();
        if(a.toCharArray().length!=8){
            System.out.println("Wrong Format");
        }else if(a.substring(2,4).equals("01")||a.substring(2,4).equals("02")||a.substring(2,4).equals("03")||a.substring(2,4).equals("20")){
            System.out.println("入学年份："+20+a.substring(0, 2)+"年");
            if(a.substring(2,4).equals("01")){
                System.out.println("学院：材料学院");
                System.out.println("班级："+a.substring(4,6));
                System.out.println("学号："+a.substring(6,8));
            }
          else   if(a.substring(2,4).equals("02")){
                System.out.println("学院：机械学院");
                System.out.println("班级："+a.substring(4,6));
                System.out.println("学号："+a.substring(6,8));
            }
          else   if(a.substring(2,4).equals("03")){
                System.out.println("学院：外语学院");
                System.out.println("班级："+a.substring(4,6));
                System.out.println("学号："+a.substring(6,8));
            }
           else if(a.substring(2,4).equals("20")){
                System.out.println("学院：软件学院");
                System.out.println("班级："+a.substring(4,6));
                System.out.println("学号："+a.substring(6,8));
            }

        }else {
            System.out.println("Wrong Format");
        }
    }
}
